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Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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3
NAWQA Cycle II Goals—Status

INTRODUCTION

In Cycle II of the National Water Quality Assessment (NAWQA) Program, one of the three primary goals of the program continues to be the assessment of water quality status—that is, to provide a nationally consistent description of current water quality conditions for a large part of the nation’s water resources. Reflecting a broad shift in focus from gathering occurrence and distribution data to better understanding water quality trends and cause-and-effect relationships (see Chapters 4 and 5, respectively), the status goal is slated to receive only 23 percent of available Cycle II resources (Gilliom et al., 2000b). This is a sharp decrease from 80 percent of resources dedicated to status assessments during Cycle I. (However, it should be noted that some resources designated to support water quality trend studies in Cycle II would have been considered status assessments in Cycle I.) Nonetheless, several changes in water quality status assessments have been proposed for Cycle II (see also Appendix A).

The November 2000 version of the NAWQA Cycle II Implementation Team (NIT) report describes the design and implementation strategy for Cycle II investigations (see Gilliom et al., 2000b). Much of this chapter, and indeed the entire report, are based on review of this internal NIT report (and previous drafts) and subsequent deliberations by the committee. At the time this report was written, a total of three status themes, each with two objectives (i.e., S1 to S6) were being planned for Cycle II. These themes are (1) to assess the water quality of the most important stream and groundwater resources not sampled during Cycle I; (2) to measure the concentrations and frequencies of occurrence of NAWQA target constituents in aquifers and streams used as sources of drinking water; and (3) to

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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assess the occurrence and distribution of contaminants not yet measured by NAWQA.

The status component is the baseline for all further NAWQA activities. The various themes, objectives, and contaminants selected for monitoring in Cycle II under the status goal of NAWQA are fundamental to the priority issues selected for national synthesis. The committee was asked in its statement of task to “assess the completeness and appropriateness of priority issues (e.g., pesticides, nutrients, volatile organic compounds, trace elements) selected for broad investigation under the national synthesis component of the program.” Before commenting on the proposed status themes and related objectives for Cycle II, it is appropriate to state that the committee supports these existing priority national synthesis topics—pesticides, nutrients, volatile organic compounds, and trace elements— and commends NAWQA for its past and ongoing work on these important topics. The committee also strongly supports the priority for ecological synthesis that was initiated in the last years of Cycle I; this is a very important topic to which NAWQA can make a significant contribution. In the sections that follow in this chapter, the committee further comments on additions to these issues and other proposed priorities.

In the context of assessing the water quality of resources not previously sampled, as well as the stated intent to focus on potable water sources, this chapter first explores the impact of reducing the number units for Cycle II on NAWQA’s ability to achieve its stated status objectives. The continued omission of lakes, reservoirs, and coastal waters in the Cycle II program (see also Chapter 2), as it will impact NAWQA’s ability to fully understand significant chemical, physical, and biological processes that affect water quality, is then explored. A significant portion of the chapter is devoted to an analysis of the last of the three status themes—that of monitoring for contaminants not previously sampled. In this regard, there are several contaminants and groups of related contaminants proposed for monitoring in Cycle II for which sampling was not conducted during Cycle I. The appropriateness of each of the proposed contaminants or contaminant groups, relative to the goals of NAWQA, is evaluated. Next, an assessment of the importance of conducting sediment monitoring as related to Cycle I activities and opportunities for Cycle II and related recommendations are provided. The chapter ends with a summary of the conclusions and recommendations of the committee concerning the status goal, themes, objectives, and corresponding investigations planned for Cycle II.

RESOURCES NOT PREVIOUSLY SAMPLED AND DRINKING WATER SOURCES

The first two new status themes of Cycle II are to assess water resources that were not sampled during Cycle I and to focus more heavily on streams and aquifers that are sources of drinking water (Gilliom et al., 2000b). The committee

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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concurs with this general strategy and notes that there is some similarity among the following objectives that the U.S. Geological Survey (USGS) has proposed to accomplish these status themes in that they separate out the different foci of the program:

Objective S1: Characterize the concentrations and distributions of NAWQA target constituents in principal aquifers and selected rivers and streams that were not included in Cycle I.

Objective S2: Characterize the concentrations of NAWQA target constituents in downgradient shallow groundwater and streams for (a) residential and commercial development in large metropolitan areas and (b) the most extensive agricultural settings in the nation.

Objective S3: Characterize the concentrations and distributions of NAWQA target constituents in aquifers and streams that have the greatest withdrawals of drinking water.

Objective S4: Improve the reporting and explanation of the potential risk to human health due to the presence of contaminant mixtures that are frequently found in current or potential sources of drinking water.

At present, the funds that will be devoted to accomplishing these four objectives constitute approximately 18.7 percent of the Cycle II NAWQA budget, according to the NIT report by Gilliom et al. (2000b). A detailed description of the proposed changes to stream and groundwater sampling to meet each of the objectives can be found in that report and an overview in Appendix A of this report. Because of the similarity among the objectives, many sites can potentially be chosen to satisfy multiple objectives. The sampling design will be the same for any new sites that are chosen in Cycle II compared to Cycle I (see Chapter 1 for an overview of surface and groundwater monitoring in Cycle I). According to Gilliom et al. (2000b), the types of stream sites that will be introduced are primarily new indicator sites that will provide more information on agricultural, urban, and pristine (reference) land uses. In particular, sampling sites located in the most rapidly growing urban regions of the nation were thought to be underrepresented in sampling in Cycle I. Sites located near water supply intakes will be added to address Objective S3.

With regard to groundwater, new sampling sites will be chosen that help complete the national trends network for groundwater and that capture the Floridan aquifer system. Other priority candidates for groundwater are shallow groundwater systems that have not yet been sampled by NAWQA and are within (1) recently urbanized portions of major metropolitan statistical areas (MSAs); or (2) important regional crop group-hydrologic landscape combinations (Winter, 1995, 2001). The regional importance of agricultural settings will be characterized based on areal extent and intensity (chemical and fertilizer use and animal density) in relation to hydrologic settings (see Gilliom et al., 2000b).

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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One important question is whether the 29 percent reduction in the number of monitored and planned study units from Cycle I to Cycle II (i.e., 59 to 42) will have a deleterious effect on achieving these objectives, especially S1 to S3. To a certain extent, the reduction in study units has been mitigated by the linear programming approach (LPA) and semiquantitative analysis (SQA) methods that were used to select the reduced suite of study units (see Gilliom et al., 2000a, and Chapter 2 for further information on LPA and SQA). Specifically, the linear program optimized the selection of study units based on drinking water use and chose study units across a representative range of hydrologic settings. The SQA approach was a ranking designed to ensure that the most significant contaminant sources are represented, that major aquifer systems are represented, and that a broad range of aquatic biological resources were included. For these reasons, the committee feels that Objectives S1 to S3 are likely to be accomplished in Cycle II, despite a reduced number of study units. As noted in Chapter 2, this is important to addressing the issues of extrapolation and aggregation of data for regional and national perspectives.

Lastly, it is evident that NAWQA and the USGS have developed considerable expertise in designing and conducting water quality status assessments in the program’s first decade of nationwide monitoring. Thus, the committee finds that the proposal, albeit limited in detail, to establish a national drinking water team within NAWQA as it enters Cycle II (Gilliom et al., 2000b) is both logical and appropriate. Such a team should help ensure that NAWQA staff achieve a consistent and high level of status assessments that are focused on potable water sources throughout the program.

Lakes, Reservoirs, and Coastal Waters in Cycle II

Objective S3 demands additional consideration of the decision made by the USGS to not monitor lakes and reservoirs under NAWQA (see also Chapter 2). In 1990, a previous National Research Council (NRC) committee suggested that long-term trends in the water quality of lakes and estuaries should receive the same level of attention as streams and groundwater. However, it did not recommend the expansion of NAWQA to include lakes and estuaries at that time because of the lack of USGS personnel and expertise in biological and chemical modeling (NRC, 1990). Instead, the report recommended that (1) lakes should be considered but only as they affect downstream water quality, (2) one or more of the first study units should include a lake that is a significant contributor to downstream water quality, and (3) mathematical models should be developed at the initial stages for study units involving lakes.

These objectives were partly met during Cycle I. Large lakes and reservoirs were essentially treated as “black boxes” with sampling done upstream and downstream of lakes and reservoirs, particularly at a dozen lakes and reservoirs that supply drinking water (Timothy Miller, USGS, personal communication, 2000).

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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In addition, some study units chosen for monitoring in Cycle I (e.g., the Willamette Basin and the Upper and Lower Tennessee River Basins) contain lakes and reservoirs that are hydrologically important to the watershed as a whole. However, given the change in focus and declining resources for status assessments during Cycle II, it is not clear what could be gained by initiating an extensive sampling program for lakes, reservoirs, and coastal waters such as estuaries in Cycle II (although identifying and focusing on contaminant sources to the systems, especially estuaries, is appropriate). Chapter 2 includes a discussion of the inherent limitations that result from excluding lakes, reservoirs, and coastal waters from widespread and regular monitoring in NAWQA. It should be noted, however, that most of these issues are not part of the stated objectives outlined above.

The committee reiterates here that the omission of lakes and reservoirs excludes an opportunity to understand significant natural physical, chemical, and biological processes that alter water quality, which is a priority of the “understanding” theme of Cycle II (see Chapter 5). Lakes and reservoirs are also a major source of drinking water for the nation. In addition, differential sedimentation, also known as sediment focusing, occurs prominently in lakes and reservoirs, in contrast to flowing waters, and this may amplify the “signal” of toxic substance accumulation. Thus, lake sediments may be the best place to look for early detection of hydrophobic toxic substances that accumulate in the aquatic environment. Recognizing this, NAWQA proposes to collect lake sediment cores in Cycle II (Gilliom et al., 2000b).

Despite the continued lack of investigation into the details of mechanisms and processes within lakes and reservoirs, there is still an opportunity for the NAWQA program to assess their impact on water quality in Cycle II. As mentioned above, sedimentation (and deposition of other contaminants) is one of the processes that is amplified by the presence of a lake in a watershed system. From measurements of inflow and outflow, NAWQA should compile information on the retention of sediments and other contaminants by lakes and reservoirs in Cycle II. The annual inflow loads and outflow loads as currently measured by NAWQA can be used to provide a measure of retention (i.e., including sediment burial, water column content, and atmospheric losses) as water passes through a lake or reservoir. Comparison of retention capabilities of various water bodies could provide guidance on where it would be beneficial to examine the processes at work in finer detail. Detailed studies could then be used to target sites with low, medium, and high retention for further study, with the ultimate goal of understanding the mechanisms to develop predictions, management strategies, and policy.

As far as lakes and reservoirs are concerned, the NAWQA program could maximize limited resources by partnering with and using data already collected by the U.S. Environmental Protection Agency (EPA). For example, NAWQA is already collaborating with EPA’s Office of Pesticide Programs to study pesti-

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

cides in lakes and reservoirs, in part to overcome existing shortcomings of the program; see also Chapter 7). The NAWQA program might benefit from collaborating with states that are conducting ambient water quality monitoring programs.

A collaborative approach also could be taken with two federal agencies that have responsibility for many of the reservoirs in the United States—the U.S. Bureau of Reclamation (USBR) and the U.S. Army Corps of Engineers (USACE). USBR and USACE reservoirs typically provide water for drinking, recreation, and irrigation, in addition to supporting aquatic life. These agencies routinely conduct water quality monitoring for a variety of uses such as aquatic life support, fish consumption, primary contact, secondary contact, drinking water supply, and agriculture. The USBR is currently assessing the quality of irrigation water supplied by its projects through its National Irrigation Water Quality Program (www.usbr.gov/niwqp/). Since irrigation return flow often empties into reservoirs (e.g., Kesterson Reservoir in the San Joaquin Valley of California and selenium poisoning of wildlife [Tanji et al., 1986]), the USBR is monitoring water quality in a number of its reservoirs. Some of the USACE districts and regions (www.usace.army.mil) have very active reservoir water quality monitoring programs. For example, the Northwestern Division of the USACE’s Missouri River Region (Omaha and Kansas City Districts) includes the Water Quality Management Program-Missouri River Region Lake Projects. Specifically, the Omaha District alone is conducting water quality studies in more than 30 lakes and reservoirs. NAWQA program personnel might be able to use these data to help assess Cycle II status, trends, and understanding goals and related themes and objectives for water quality in selected study units.

The NAWQA program has been collaborating with the National Oceanic and Atmospheric Administration (NOAA) in estuarine research (see Chapter 7 for further information). In its study units that are tributary to estuaries, NAWQA has been measuring inflows and chemical fluxes. A recent study by Bricker et al. (1999) used NAWQA data to establish nutrient loadings to a number of the nation’s estuaries. In addition, the SPARROW (Spatially Referenced Regressions on Watershed Attributes) model (Smith et al., 1997) was used to provide first-order estimates of nutrient loads for the year 1987 from five major sources: fertilizer, livestock wastes, point sources, atmospheric deposition, and non-agricultural sources (Bricker et al., 1999). Preston and Brakebill (1999) reported on the application of SPARROW to assess nitrogen loading in the Chesapeake Bay watershed. These are just a few examples of how the Cycle II NAWQA program can extend itself to study water quality issues in the nation’s coastal waters and estuaries by partnering with other agencies such as NOAA.

Recommendations
  • Given the reduction in resources that necessitated a smaller suite of Cycle II study units, more emphasis on sampling in lakes, reservoirs, and estuaries

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

than already planned for Cycle II is not feasible. Hence, opportunities for partnering with other agencies should be sought. For example, NAWQA study units should focus on collaborating with and using data collected by other organizations, such as state agencies, EPA, USBR, USACE, and NOAA, in assessing the importance of pollutant loadings and surface water-groundwater interactions related to water quality in lakes, reservoirs, and estuaries. In this manner, a better characterization of their water quality and some degree of understanding of the relevant processes may be obtained with a minimum of NAWQA expenditures.

  • Current sampling in lakes and reservoirs that are important public supply sources should be maintained in Cycle II; other important lake-reservoir public supply sources should be included if resources become available (this might involve a reassessment of which lakes or reservoirs to sample). As noted in Chapter 2, the LPA-SQA methodology could be used to help determine which lakes and reservoirs to study.

  • From measurements of inflow and outflow, NAWQA should compile information on the retention of sediments and other contaminants by lakes and reservoirs.

Human Health Risks

Objective S4 of the Cycle II design guidelines, as currently stated, represents a significant departure from the USGS’s traditional areas of focus because it ventures into human health risk assessment. The committee emphasizes that the strength of NAWQA is in its ability to design sound sampling strategies; to use standardized, proven analytical methodologies to analyze those samples, and to evaluate the data for possible trends, causative factors, and so forth. In contrast, toxicological research and health risk assessment are more appropriately the purview of other agencies such as the National Institute of Environmental Health Science and its National Toxicology Program, the National Cancer Institute, the EPA, and the Agency for Toxic Substances and Disease Registry. The committee feels strongly that the area of human health risk assessment should not be an activity of the NAWQA program. Rather, NAWQA should concentrate on providing good water quality and related data and thorough analyses of those data. In this regard, the committee notes that NAWQA did an excellent job of synthesizing water chemistry data and biological data to assess associations between contaminant occurrence and evidence of potential endocrine disruption in fish (Goodbred et al., 1996). In conjunction with other local, state, and federal agencies, further assessments such as this might be accomplished in Cycle II, with NAWQA helping to further define hypotheses that should be toxicologically evaluated.

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×
Recommendation
  • NAWQA should consider significantly revising the language of Objective S4 to fit its strengths, for example: “Describe the occurrence and co-occurrence of contaminants and contaminant mixtures in the environment that should be considered by other agencies for toxicological and health effects research and risk assessments.”

CONTAMINANTS NOT PREVIOUSLY SAMPLED

Although there will be a major decline in the proposed budget for status assessments in Cycle II versus those conducted in Cycle I, it has been proposed that NAWQA expand to include a third new status theme for contaminants that have become high national priorities in the last decade (Gilliom et al., 2000b). With respect to contaminants not previously sampled, NAWQA proposes the following two objectives:

Objective S5: Characterize the frequencies of occurrence and concentrations of emerging contaminants in streams and aquifers that are sources of drinking water and in streams representative of potential ecological effects from urban and agricultural land uses.

Objective S6: Characterize the concentrations and distributions of total and methyl mercury in streams that have the greatest potential for human exposure to mercury through consumption of drinking water or fish.

A number of potential candidates have been suggested for monitoring in Cycle II study units to include methyl mercury, waterborne microbial pathogens, new pesticides, pharmaceutical products, and high-production-volume industrial chemicals (Gilliom et al., 2000b). The approach suggested to accomplish this objective is to conduct a pilot evaluation of selected contaminants that are of high national priority, for which there are established and reliable analytical methods in a small subset of the study units.

Because of the limited funds available for such a program, it is logical to limit the monitoring to those contaminants for which analytical methods exist. However, the very nature of monitoring for emerging contaminants almost always requires the development of new analytical methods for sampling in the field and/ or laboratory analyses. Thus, the USGS’s desire to monitor only those emerging contaminants for which there are established analytical methods presents a somewhat difficult situation.

When selecting contaminants to monitor, consideration should be given to the status of existing and planned monitoring programs being conducted by other entities. In the early, exploratory stages of monitoring for a new contaminant, it may be prudent to defer to other organizations that have greater resources and

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

expertise to conduct developmental work on specific methods. In this regard, NAWQA should focus on filling gaps in knowledge (e.g., by providing information in previously unstudied areas or by providing information on the temporal and spatial variability of the contaminant’s occurrence and concentrations). The decision on which additional contaminants to study should be made with direct input from the EPA and other agencies interested in water quality, so that those most relevant to important regulatory and policy issues are identified. In addition, consideration should be given to the evidence for known or suspected impacts on human or environmental health. For example, it is well documented that human pathogens in water cause thousands of cases of illness annually in the United States (e.g., Barwick et al., 2000; see more below). On the other hand, the potential impacts that trace quantities of pharmaceuticals and their degradation products in water have on human or ecological health are uncertain (Daughton and Ternes, 1999; Halling-Sorensen et al., 1998).

NAWQA personnel have already used ranking schemes to help determine which pesticides and volatile organic compounds (VOCs) should be included in the program (Miller and Wilber, 1999). However, the entire suite of constituents for which monitoring is being conducted, as well as those under consideration for monitoring, must be considered as a whole. In other words, NAWQA should develop a procedure whereby contaminants can be evaluated or ranked against one another in a manner that will allow decisions about which contaminants to include in the monitoring program to be made on an objective basis. For example, a method has to be developed whereby specific pathogens can be compared to specific pesticides so that their relative importance for monitoring purposes can be determined. Furthermore, development of such a method or procedure should involve the direct participation or input of agencies interested in water quality such as the EPA.

The intrinsic difficulty of identifying a manageable list of constituents for monitoring in Cycle II raises the question of what kind of process or method is best suited to this type of judgment. In this regard, the committee notes that a recent NRC report, Classifying Drinking Water Contaminants for Regulatory Consideration (NRC, 2001), recommended and convincingly demonstrated a novel approach to help EPA sort thousands of potential drinking water contaminants of all types (e.g., chemicals, microorganisms, radionuclides) into two discrete sets—one that may undergo research or monitoring of some sort preparatory to an eventual regulatory decision and another much larger set that will not. That committee considered three broad types of strategies for accomplishing such a difficult task: expert judgment, rule-based systems, and prototype classifiers. Based on its review, that committee decided that a prototype classification approach using neural networks or similar methods would seem to be an innovative and appropriate means for EPA to consider. Although this committee does not necessarily recommend that NAWQA develop such an approach to assess

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

and cull a very large set of constituents to a much smaller set for monitoring in Cycle II study units, it does note the flexibility of the approach.

Criteria that the NAWQA team may want to consider in developing the ranking scheme may include human health effects, ecological effects, mass of the contaminant released into the environment, analytical costs, availability of established detection methods, and the contribution that the USGS can make to existing monitoring efforts. A discussion of particular groups of related high-priority contaminants that are being considered for monitoring in Cycle II is provided below.

Recommendations

  • NAWQA should focus on filling gaps in knowledge (e.g., by providing information in previously unstudied areas or by providing information on the temporal and spatial variability of the contaminant’s occurrence and concentrations), rather than on new contaminants for which methods have not been developed.

  • The decision about which additional contaminants to study should be made with direct input from the EPA and other agencies so that the most important contaminants from a regulatory and policy-making standpoint can be monitored.

  • The NAWQA team should develop a procedure either jointly or with the direct input of EPA or other federal agencies whereby all contaminants can be evaluated and/or ranked according to a variety of criteria, including the availability of analytical methods, known or suspected health or ecological effects, and other factors.

Pesticides, Pharmaceuticals, and High-Production-Volume Industrial Chemicals

In part to address Objective S5, the USGS has considered adding several new pesticides and groups of related chemicals, such as pharmaceutical products, to the NAWQA list of analytes (Gilliom et al., 2000b). Three new groups of pesticides that have high usage and can easily be added to existing analytical methods or for which reliable methods can be established are proposed for addition. First, with some improvements in methods, a number of important organophosphate insecticides and degradates will be added. Further, using newly developed and validated methods, various sulfonyl urea herbicides may be included. The latter represents an important addition because the sulfonyl ureas are a new class of pesticides whose use is rapidly expanding as many older pesticides are being discontinued in the United States. However, their environmental fate is not well understood. Lastly, NAWQA also proposes to add an immunoassay method to analyze for glyphosate. Glyphosate is one of the most widely used herbicides, and its current standard analytical method is problematic and expensive. An

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

immunoassay method, if proven reliable in NAWQA, could provide significant benefits to various regulatory monitoring programs as well. The committee agrees that all three groups of pesticides are appropriate and warrant addition to the list of monitored contaminants in Cycle II.

In contrast, the committee strongly recommends that pharmaceuticals and their degradates should not be added to NAWQA’s analytical list until reliable sampling protocols and analytical methods can be validated. As in past cooperative efforts, hopefully NAWQA can collaborate internally with the USGS’s Toxic Substances Hydrology Program and/or National Research Program to help refine and establish the requisite sampling and analytical approaches, and then move into an assessment study.

Similarly, the consideration of adding high-production-volume (HPV) industrial chemicals must be considered carefully. Many important HPV contaminants are already included in NAWQA’s VOCs, trace metals, and elements monitoring. Where new chemicals can be accommodated easily in existing methods they might be included. If they will necessitate extensive protocol or methods development the committee suggests that NAWQA collaborate with others for the development work. Only if a particular HPV chemical is a clear priority (e.g., has known or potential human health or environmental impacts) can NAWQA consider expending its limited resources for such development and monitoring efforts. If other agencies provide support for needed development and monitoring work, these might be accommodated in a collaborative project.

Recommendations
  • NAWQA should not add pharmaceuticals to the list of contaminants to be monitored in Cycle II until reliable sampling protocols and analytical methods can be validated.

  • NAWQA should carefully consider any additions of HPV industrial chemicals to its analytical list of monitored contaminants. Similar to new pesticides, where HPV chemicals can be accommodated easily by existing methods they might be added. Like pharmaceuticals, they should not be added until protocols and methods are validated, unless there are urgent reasons (or external support) to do so.

Methyl Mercury

Mercury is one of the most widespread contaminants in our nation’s watersheds and is associated with adverse health effects in exposed populations. Bioaccumulation of mercury (in the form of methyl mercury [MeHg]) often results from trophic transfer from contaminated sediments and water (Morel et al., 1998). Forty states have issued fish consumption advisories because of MeHg contamination—more than any other substance (Brunbaugh et al., 2000). A

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

limited bed sediment and tissue sampling effort focused on methyl mercury is planned to be conducted once during the high-intensity phase of each Cycle II study unit (Gilliom et al., 2000b). More specifically, each study unit will select 8 to 10 stream sites representing the following three conditions: (1) background sites where mercury input is thought to be low with little wetland; (2) low potential input but high wetland areas; and (3) urban sites with a range of wetland areas. In the selection and monitoring of sites, atmospheric inputs of mercury should be considered. (As noted in Chapter 7, the National Trends Network of the USGS’s National Atmospheric Deposition Program has collected mercury deposition data that can be used.)

At each site, one composite bed sediment sample will be analyzed for total mercury and MeHg and another for acid-volatile sulfides (AVSs); fish fillets from a top predator will be analyzed for total mercury (Gilliom et al., 2000b). This design is based on and expands on the results of a pilot study examining mercury contamination in fish at 106 sites in 20 watersheds (Brunbaugh et al., 2000). That study concluded that a four-variable model (MeHg in water, percent wetland, pH, and AVS in sediments) best predicted bioaccumulation of mercury in fish (tissue concentration of mercury versus length). When correlations between bioaccumulation of mercury and individual variables were determined, MeHg concentration in water and in sediment, total mercury in water, and pH were significant. Correlations with total mercury and AVSs in sediment were not significant. Given these findings, it appears that MeHg concentration in water should also be determined. Because of its widespread occurrence and potential health effects, the committee believes that MeHg is an important contaminant to include in Cycle II monitoring. Furthermore, the sampling design proposed by the USGS (Gilliom et al., 2000b) is adequate, except that consideration should be given to sampling MeHg concentration in the water, since the pilot study indicates that to be a good predictor of MeHg contamination in fish.

Recommendation
  • In the selection and monitoring of MeHg sites already planned for Cycle II, consideration should be given to atmospheric inputs of mercury. NAWQA should also consider sampling MeHg concentration in the water since that appears to be a good predictor of bioaccumulation of mercury in fish.

Microbiological Monitoring

The mission of the Water Resources Division (WRD) of the USGS is to provide reliable, impartial information needed to understand the nation’s water resources. Among other goals, the WRD actively promotes the use of this information by decision makers to protect and enhance water resources for human health, aquatic health, and environmental quality and to effectively manage

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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groundwater and surface water resources for domestic, agricultural, commercial, industrial, recreational, and ecological uses.

If one assesses the NAWQA program’s goals in the context of the mission of the WRD, it becomes apparent that it is essential that the biological component of the program be increased. To obtain information that will enable decision makers to protect water resources for human and aquatic health, it is essential to have a better understanding of the biological components of those resources. Likewise, effectively managing water resources for domestic, recreational, and ecological purposes requires data on the biological quality as well as the chemical and physical quality of surface water and groundwater. The WRD, through the NAWQA program, is in a unique position to gather these data, both temporally and spatially.

From the standpoint of human health, it is well documented that microorganisms present a significant public health risk. Up to 90 percent of all reported waterborne disease outbreaks in the United States are caused by pathogenic microorganisms, rather than chemical contaminants (Barwick et al., 2000, Craun, 1991; Herwaldt et al., 1992; Kramer et al., 1996; Levy et al., 1998; Moore et al., 1993). Since 1971, more than 570,000 people have been documented as having become ill from microorganisms in drinking water as summarized in Table 3-1. There have also been a number of outbreaks associated with recreational water in natural settings such as lakes and rivers (Table 3-2). The health cost of outbreaks caused by the waterborne protozoa Giardia is estimated to be between $1.2 billion and $1.5 billion per year (EPA, 1997b), while the cost of the 1993 Milwaukee Cryptosporidium outbreak is estimated to have exceeded $54 million (Health and Environmental Digest, 1994). The EPA (1997a) estimates the cost to drinking water facilities for improved microbial treatment to be about $20 billion over the next 20 years, with about half of that needed immediately. Obtaining information on the occurrence of microorganisms in surface water and groundwater is critical to determining ways to prevent outbreaks. In addition, understanding and explaining the major factors and processes affecting water quality (the main effort in Cycle II of NAWQA) cannot be fully addressed without considering waterborne pathogens.

Contamination of public drinking water systems (including microbial contaminants) is currently regulated at the national level by the Safe Drinking Water Act (SDWA) of 1974, which was most recently amended in 1996. Microbial contamination of drinking water supplies is addressed by several existing and proposed rules, including the Surface Water Treatment Rule (SWTR) of 1989, the Interim Enhanced Surface Water Treatment Rule (IESWTR) of 1999, the Information Collection Rule (ICR) of 1996, the Total Coliform Rule (TCR) of 1989, and the proposed Ground Water Rule. For example, the IESWTR builds on the SWTR and includes several new provisions, such as a health goal of zero occurrence for Cryptosporidium; a minimum 99 percent removal of Cryptosporidium for filtered water supplies; and sanitary surveys for all surface water systems regardless of size.

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

TABLE 3-1 Causative Agents of Waterborne Disease Associated with Drinking Water in the United States, 1971-1998

 

Outbreaks

Illnesses

Causative Agent

Number

Percent of Total

Number

Percent of Total

Gastroenteritis, unknown causea

334

48.1

82,076

14.4

Giardia

125

18.0

28,657

5.0

Chemical poisoning

74

10.6

4,360

0.8

Shigella

46

6.6

9,395

1.6

Viral gastroenteritis

29

4.2

13,441

2.4

Hepatitis A virus

26

3.7

772

0.1

Campylobacter

15

2.2

5,456

1.0

Salmonella typhimurium

13

1.9

2,995

0.5

Cryptosporidium

12

1.7

421,371

73.9

Salmonella typhi

5

0.7

282

< 0.1

Yersinia

2

0.3

103

< 0.1

Toxigenic Escherichia coli

7

1.0

1,442

0.3

Vibrio cholera

2

0.3

28

< 0.1

Chronic gastroenteritis

1

0.1

72

< 0.1

Dermatitis

1

0.1

31

< 0.1

Amebiasis

1

0.1

4

< 0.1

Cyclospora

1

0.1

21

< 0.1

Plesiomonas shigelloides

1

0.1

60

< 0.1

Total

695

100.0

570,566

100.0

aMicrobial in origin.

SOURCE: Data from Barwick et al., 2000; Craun, 1991; Herwaldt et al., 1992; Kramer et al., 1996; Levy et al., 1998; Moore et al., 1993.

The EPA recently completed a negotiated rule-making process that led to recommendations about what it should propose under the Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). Under the LT2ESWTR, EPA intends to propose (1) initial source water monitoring requirements to determine whether additional treatment for Cryptosporidum would be required and (2) a second round of source water monitoring, six years after the initial assessments, to determine if initial source water quality conditions have changed to warrant additional treatment. The negotiating committee also recommended that EPA develop national water quality criteria for microbial pathogens for stream segments designated by states or tribes for drinking water use (under the Clean Water Act [CWA] authorities).

The EPA also recently established a “Beach Action Plan” as a multiyear strategy to improve the monitoring of recreational water quality and the commu-

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

TABLE 3-2 Causative Agents of Waterborne Disease Associated with Recreational Water (Natural Settings) in the United States, 1991-1998

 

Outbreaks

Illnesses

Causative Agent

Number

Percent of Total

Number

Percent of Total

Gastroenteritis, unknown causea

10

19.23

1,101

30.26

Naegleria fowleri

10

19.23

10

0.27

E. coli O157:H7

9

17.31

293

8.05

Shigella sonnei

9

17.31

1,111

30.53

Giardia

4

7.69

65

1.79

Cryptosporidium

3

5.77

429

11.79

Dermatitis

3

5.77

152

4.18

Norwalk virus

3

5.77

103

2.83

Leptospira

1

1.92

375

10.31

Shigella flexneri

1

1.92

35

0.96

Total

52

100.00

3,639

100.00

aMicrobial in origin.

SOURCE: Data from Barwick et al., 2000; Kramer et al., 1996; Levy et al., 1998; Moore et al., 1993.

nication of public health risks associated with pathogen-contaminated recreational rivers, lakes, and ocean beaches (EPA, 1999). Furthermore, in October 2000, the Beaches Environmental Assessment and Coastal Health Act of 2000, or “BEACH” act, was signed into effect. Among other requirements, it amends the Clean Water Act to require ocean, bay, and Great Lakes states to comprehensively test recreational beach waters for waterborne pathogens and to notify the public when contamination levels make beach water unsafe for recreational uses.

As evident from Tables 3-1 and 3-2, a number of different microorganisms have been documented to cause waterborne disease outbreaks. It is not practical to monitor all of the microorganisms that could potentially be in water. Thus, some method for determining which microorganisms would act as signals of a potential health risk must be devised. For several decades (as reflected by early drinking water regulations such as the TCR), the drinking water community has relied on coliform bacteria as indicators of the microbiological quality of water. In theory, if coliform bacteria are present pathogenic microorganisms may be present and the appropriate precautionary measures must be taken to protect public health. Conversely, the absence of coliform bacteria is meant to signify that the water does not contain pathogenic microorganisms. Over the last several years, it has become clear that this paradigm does not always hold true—pathogens have been detected in waters that do not contain detectable concentrations of

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

coliform bacteria, sometimes at levels that can cause a disease outbreak. Thus, it is clear that a different and more reliable method for assessing the microbiological quality of water must be developed. Indeed, the specific pathogen monitoring requirements of recent drinking water supply regulations (e.g., the IESWTR) recognize that relying on indicator organisms such as coliform bacteria may not be sufficient to protect public health.

One potential alternative to monitoring for coliform bacteria is to monitor for individual pathogens (though this is often considered prohibitively expensive). Another alternative is to monitor for alternative indicators, such as coliphages (viruses that infect bacteria) or for spores of the bacteria Clostridium perfringens, which are ubiquitous and survive longer than coliform bacteria in the aquatic environment. For groundwater systems, monitoring for coliphages (rather than human viruses) as indicators of fecal contamination instead of or in addition to coliform bacteria has been proposed (EPA, 2000c). Coliphages are about the same size as viruses that infect humans, in contrast to coliform bacteria, which are typically tens to hundreds of times larger than viruses. This allows bacteria to be more easily removed as water percolates through soil. In addition, coliphages have similar survival characteristics to human viruses in the environment, while coliform bacteria tend to be inactivated more rapidly.

For these and other reasons, many scientists believe that monitoring for specific pathogens, rather than continuing to rely on indicator microorganisms, is essential to accurately assess the microbiological quality of water (EPA, 2000b).

The latest Cycle II NIT report’s (Gilliom et al., 2000b) recommendations for microbiological monitoring represent a significant change from earlier proposals. An earlier proposal (Francy et al., 2000a) incorporated monitoring for both indicator organisms and specific waterborne pathogens for streams and groundwater. However, the latest proposed strategy provided to the committee is to monitor Cycle II stream sampling sites located near public water supply intakes just for Escherichia coli to determine seasonal patterns of concentrations (William Wilber, USGS, personal communication, 2001). The groundwater monitoring program will include monitoring for E. coli, total coliform bacteria, and coliphages.

While E. coli can be an important water- and foodborne pathogen and serve as an indicator of the presence of enteric pathogens, its presence or absence in the water will provide little information about the presence or absence of other waterborne pathogens of concern. Thus, the proposed reduction is a significant concern to the committee.

The strength of the currently proposed program is that efficient use of limited resources will be made by monitoring for the indicator organisms (analyses for which are at least an order of magnitude less expensive than for individual pathogens). Temporal sampling will be conducted, which is critical for microbiological sampling. The microorganisms chosen for study are compatible with those chosen for other previous and ongoing studies, allowing for easy comparison to earlier work. The analyses of groundwater samples for coliphages in

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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addition to indicator bacteria will provide critical information about the vulnerability of those wells to contamination by viruses of human health significance. Finally, the majority of the sampling can be performed by USGS personnel with little or no additional training (Donna Francy, USGS, personal communication, 2000).

This current proposal also has several weaknesses. First, and most significantly, is the lack of any specific pathogen (e.g., enteric viruses, Cryptosporidium, Giardia) monitoring in the program. As noted previously, the presence or absence of “indicator” organisms such as E. coli in water does not necessarily have a direct correlation with the presence or absence of pathogenic microorganisms in water. There is a critical need to obtain information about the co-occurrence of indicators and pathogens in a given water body at a given time. There is also a need to evaluate the ability of an indicator to indicate the vulnerability of a site to microbiological contamination. In other words, it would be useful to determine whether the presence of indicators in a well is correlated with the presence of pathogens in that well at some time—not necessarily at the same time as the indicators were found. This is especially significant for groundwater systems, where contamination may be more sporadic over time. The committee recommends that if the current proposal is used for the microbiological monitoring program, any monitoring sites that have indicator-positive samples should also be tested for the presence of specific pathogens. A subset of sites that are indicator-negative should also be tested for pathogens in a manner that will allow statistical analysis of the data.

Another potential weakness of the proposed monitoring program is that some methods development may be necessary to optimize recovery of microorganisms from the samples, which will divert resources from the program. Because the NIT report does not specify the exact methods to be used, the strains of bacteria being considered as hosts for coliphage infection, or more of the details of the methods, it is difficult to determine whether development of the methods will be a significant issue.

While the committee recognizes the limitations imposed by lack of resources, it strongly recommends that NAWQA reconsider its earlier proposal (described below) for pathogen and indicator bacteria monitoring. The impact of waterborne microorganisms on human health is well documented, and such a significant group of waterborne contaminants should not be excluded from a national monitoring program. NAWQA is well positioned to contribute significantly to the knowledge base on the occurrence of microorganisms in water, especially with respect to their temporal occurrence.

The previous recommendations for microbiological monitoring made by the USGS incorporate monitoring for both indicator organisms and pathogenic organisms (Francy et al., 2000a). The proposed strategy was to monitor all surface water sites for E. coli and then to perform monitoring for other indicators (coliphages and Clostridium perfringens) and selected pathogens (Crypto-

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

sporidium, Giardia, and enteric viruses) at a subset of the sites. In this way, the costs of the sampling program would be significantly reduced (compared to monitoring at all sites). The hope was that a correlation between indicator presence and pathogen presence could be established at those sites at which all microorganisms are monitored, enabling an assessment of the quality at sites where only indicator sampling is performed. The same strategy was proposed for groundwater wells, where sampling for bacterial indicators (total coliform bacteria, E. coli, and enterococci) would be performed at all sites, and coliphage and enteric virus monitoring would be performed at a subset of the sites.

This strategy was developed based on the results of a pilot monitoring project, in which microbiological analyses were performed on samples collected from six of the NAWQA study units (Francy et al., 2000b). For surface water sites, samples were analyzed for two groups of indicator bacteria and one indicator bacterium: total coliform bacteria, fecal coliform bacteria, and Clostridium perfringens. Significant correlations were found between the concentrations of these indicators and the following water quality characteristics: dissolved organic carbon, several nitrogen species, total phosphorus, chloride, suspended sediment, and specific conductance. For groundwater samples, analyses were performed for the following indicators: total and fecal coliform bacteria, Clostridium perfringens, and coliphages. Because of technical difficulties, coliphage results were not usable. Examination of the results revealed that a significant correlation existed between the detection of total coliform bacteria and aquifer type (p < .04). The association between total coliform bacteria detection and land use was slightly less significant (p < .07). Based on this limited study, the authors concluded that a greater diversity of sites and more detailed information about the sites (such as might come with full implementation as part of NAWQA) would be needed for an adequate assessment of the factors that affect the microbiological quality of water.

The strengths of the proposed program are that resources will be maximized by monitoring for the pathogenic organisms (which cost at least an order of magnitude more than the indicator microorganism per sample) at only a subset of the sites. The committee also recommends that any groundwater monitoring sites that have indicator-positive samples should be tested for the presence of pathogens. A subset of sites that are indicator-negative should also be tested for pathogens in a manner that will allow multivariate statistical analysis of the data, such as was performed by Francy et al. (2000b).

Temporal sampling will be performed, which is critical for microbiological sampling. The microorganisms chosen for study are compatible with those chosen for previous and ongoing studies, allowing for easy comparison to earlier work. Finally, the majority of the sampling can be performed by USGS personnel with little or no additional training (Donna Francy, USGS, personal communication, 2000).

There are also some potential weaknesses of this more detailed proposal.

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

First, all virus assays were proposed to be performed using PCR (polymerase chain reaction) only. This method does not allow one to distinguish between infective and noninfective viruses. Second, to assess accurately the vulnerability of a groundwater well to virus contamination, it is essential that viral analyses of the water be performed. The difference in size between bacteria (2-5 µm) and viruses (25-50 nm) is so great that viruses may be able to move through porous media that would not permit bacterial transport. The survival of enteric viruses, in general, is also longer than that of enteric bacteria. Therefore, the absence of bacteria in a groundwater sample does not necessarily indicate a lack of vulnerability to contamination by fecal viruses. The committee strongly recommends that coliphage analyses be performed at all groundwater wells. Finally, some methods development may be necessary to optimize recovery of microorganisms from the samples, which will divert resources from the program. (This could be considered a strength of the program in that methods can be tested on a wide variety of sample matrices.)

Recommendations
  • Waterborne pathogens are very important to human health, and NAWQA can potentially make significant contributions to our understanding of their occurrence and distribution in the nation’s waters. To this end, NAWQA should reconsider its previously proposed microbiological sampling program that would include more extensive sampling.

  • Groundwater sites that have indicator-positive samples should be tested for the presence of specific waterborne pathogens. A subset of sites that are indicator-negative should also be tested for pathogens in a manner that will allow multivariate statistical analysis of the data, as performed in the study by Francy et al. (2000b).

IMPORTANCE OF CONDUCTING SEDIMENT MONITORING

Disturbing the soil through tillage, cultivation, construction, and other land management activities increases the rate of soil erosion. Dislocated soil particles can be carried in runoff and eventually reach surface water resources, including streams, rivers, lakes, reservoirs, and wetlands. While sediment deposition at the mouths of rivers can create valuable wetlands such as the Mississippi River Delta, suspended and deposited sediments affect the utility of water resources in a number of adverse ways. Accelerated reservoir siltation reduces the useful life of reservoirs. Sediment can clog roadside ditches and irrigation canals, and block navigation channels. By raising streambeds and burying stream-side wetlands, sediment increases the probability and severity of floods. Suspended sediment can increase the cost of water treatment for municipal and industrial water uses. Suspended sediment increases the turbidity of water, possibly affecting aquatic

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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life and the appearance of water resources to recreationists. Sedimentation of river bottoms and wetlands can destroy habitat vital to aquatic organisms. Many toxic materials can be tightly bound to clay and silt particles that are carried into water bodies, including some nutrients, agricultural chemicals, industrial wastes, metals from mine spoils, and radionuclides (Osterkamp et al., 1998). When sediment is stored, the sorbed toxins are also stored and become available for assimilation. Research on the status and trends of sediment in water systems, the impacts of sediment on aquatic life, and the sources of sediment is important because of its many substantial economic impacts on water users.

Sediment is the largest contaminant of surface water by weight and volume (Koltun et al., 1997), and it is routinely identified by states as the leading pollution problem in rivers and streams (EPA, 1998). The most recent “305(b)” water quality reports submitted by the states to EPA (as required under the CWA) indicate that sediment is a leading pollutant in 38 percent of the surveyed rivers and streams that were found to be impaired (23 percent of all rivers and streams were surveyed, and 35 percent were found to be impaired) (EPA, 2000b). Similarly, the 1998 “303(d)” reports of impaired waters pinpoint sediment as the leading cause of water impairments in the nation, affecting more than 6,000 water bodies or stream reaches (EPA, 2000a).

Ecological Impacts and Associated Economic Costs

Suspended sediment affects aquatic organisms both directly and indirectly. High suspended sediment loads can dramatically increase mortality rates of invertebrates and fish (Newcombe and MacDonald, 1991). Accumulation of fine sediments on body surfaces and gills adversely affects macroinvertebrates (Lemly, 1982), and reduction in the feeding efficiency of fish is observed when turbidity (suspended sediment) is elevated (Barrett et al., 1992). Lower rates of primary productivity as a consequence of turbidity-limited light penetration result in reductions in food resources supporting aquatic food webs (Waters, 1995).

The effects of excess sediments deposited in the stream channel are arguably even more profound than the effects of suspended sediments because essential feeding, breeding, and refuge habitats are altered. Accumulated sediment covering insect grazing habitat leads to increased rates of drift (Rosenberg and Wiens, 1978). Sediment deposition results in more homogeneous habitat, which is linked to reductions in species richness (Townsend et al., 1997). For example, insect diversity decreases as the mean size of bed material declines (Shields and Milhous, 1992). In addition to decreasing the food resources available to fish, excess sedimentation fills interstitial spaces that are essential for successful reproduction in many fish species (Waters, 1995). This has been demonstrated numerous times for salmonids, but many other fish also require clean gravel substrates for spawning (Etnier and Starnes, 1993). Many stream fish (especially juveniles) utilize the spaces between rocks as resting sites and as over-wintering

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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refuges, which are eliminated as these spaces are filled with sediment (Bjornn and Reiser, 1991; Newcombe and MacDonald, 1991). Overall, excess sediment can reduce biodiversity of aquatic resources and may pose threats to threatened and endangered species if it occurs in critical habitats. For example, soil erosion from logging, grazing, and agriculture could pose threats to remaining salmon habitat in the Pacific Northwest, hindering recovery efforts (Aillery et al., 1996).

An indication of the damage to water resources from sediment is the value placed on reducing sediment’s impacts. Ribaudo (1989b) estimated that the Conservation Reserve Program, a U.S. Department of Agriculture (USDA) program for retiring highly erodible cropland, could result in $21.4 million per year in benefits to freshwater recreational fishing from reduced sedimentation.

Other types of water-based recreation besides fishing can be affected by sediment, as demonstrated by numerous examples. Macgregor (1988) found that sedimentation at 46 Ohio State Park lakes resulted in welfare losses to boaters ranging from less than $0.01 to $11.95 per ton of sediment, with an average of $0.49 per ton. Sedimentation in recreational lakes has also been found to affect lakeside property values (Bejranonda et al., 1999). Feather and Hellerstein (1997) looked at erosion reduction on private lands in the United States from 1982 to 1992 and estimated benefits to water-based recreation of $373 million, including fishing, boating, and swimming. They also found that almost 88 percent of the benefits accrued to recreation on lakes.

Reservoir sedimentation is another consequence of soil erosion. Survey data collected by the USDA and the U.S. Department of the Interior (USDI) indicate that in the 1970s and early 1980s, sedimentation eliminated slightly more than 0.2 percent of the nation’s reservoir capacity each year (Crowder, 1987). Annual economic costs, based on replacing lost capacity, were estimated to be $819 million per year (1980 dollars).

Most municipal water treatment plants must filter water before it is treated and distributed. The greater the amount of suspended sediment, the more expensive is this filtration. Annual costs to the water treatment industry from sediment were estimated to be between $458 million and $661 million in 1984 (Holmes, 1988). A study of treatment costs for a single treatment plant with a capacity of 65 million gallons per day (MGD) in an urban watershed found that reducing suspended sediment and associated water turbidity from an average of 23 NTU (nephelometric turbidity units) to 1-2 NTU would reduce capital and operations and maintenance costs by more than $2 million per year (Davis, 1999). Reducing turbidity to an average of 9 NTU would reduce costs by more than $700,000 per year.

Sedimentation in navigation channels increases the costs to shipping by increasing transit time and decreasing the amount of cargo that can be carried. The USACE incurred dredging costs of more than $500 million per year for maintaining navigation channels over the period 1992-1998 (Cecil Davison, Economic Research Service, USDA, personal communication, 2000). The Ohio Depart-

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

ment of Natural Resources estimated direct off-site cost of removing soil erosion sediment in Ohio at $160 million per year (Bejranonda et al., 1999).

Although these are not a measure of total damages, citizens in North Carolina valued the existence of urban erosion and sediment pollution programs at between $7.1 million and $14.9 million per year (Paterson et al., 1993). Total damages from sediment due to erosion have been estimated to be between $5 billion and $17 billion per year in the United States (Ribaudo, 1989b). These estimates include damages or costs to navigation, reservoirs, recreational fishing, water treatment, water conveyance systems, and industrial and municipal water use.

Current Information on Sediment Status and Trends.

A lack of monitoring data to evaluate control actions aimed at reducing the impacts described above has made it difficult or impossible to assess the effectiveness of erosion and sedimentation control policies, leaving open the question of whether public resources were well spent (GAO, 1990). The USDA spends tens of millions of dollars annually on conservation programs to combat soil erosion. The Conservation Reserve Program alone was estimated to provide between $2 billion and $5 billion in water quality benefits from reduced sedimentation; however, these benefits could have been higher through better targeting (Ribaudo, 1989a,b). Current estimates of soil erosion and the impacts of conservation practices on water quality are based on models, primarily the Universal Soil Loss Equation (Wischmeier and Smith, 1978). Unfortunately, there is little physical, field-based evidence to verify model estimates of erosion or its impacts on water quality. Trimble and Crosson (2000) claim that “. . . we do not seem to have a truly informed idea of how much soil erosion is occurring in this country, let alone of the processes of sediment movement and deposition.” They recommend a comprehensive national system of monitoring soil erosion and downstream sediment movement, including suspended sediment and bedload.

This is not meant to imply that sediment data are never collected. In fact, such data are collected from numerous sites in North America and have been used to assess national trends in suspended sediment and to show that sediment concentrations have trended downward in some regions (e.g., Smith et al., 1993). However, these data are deficient in several ways. Sampling sites are operated for a variety of purposes and do not represent a sampling network from which regional or national inferences about suspended sediment can be made (e.g., see Osterkamp et al., 1998; Parker et al., 1997). Federal funding is not available to measure bedload, which may account for one-half or more of the total sediment load in some streams (Osterkamp et al., 1998). Also, most sediment sampling does not include sorbed chemical loads.

From a purely scientific standpoint, adequate sediment monitoring data in streams are a prerequisite to understanding the associated chemical and biological systems. Increasingly sophisticated studies of the chemistry and ecology of

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

river systems have placed additional demands on our understanding of the physical system of rivers, which includes sediment transport processes. However, several recent federal water quality protection efforts with practical applications would also benefit from improved sediment sampling data, such as the EPA’s Total Maximum Daily Load (TMDL) Program (discussed later). There is an urgent need among state and federal agencies to evaluate the magnitude of adverse impacts on designated beneficial uses of a stream reach related to sediment and to develop appropriate actions to mitigate these impacts.

Sediment Monitoring and Assessment in Cycle I and Cycle II of NAWQA

Occurrence and distribution assessment of water quality constituents was the major NAWQA Cycle I activity, with suspended sediment identified as one of the water quality issues to be addressed (Gilliom et al., 1995). The approach taken by NAWQA to assess the water quality of streams is based on three interrelated components: water column, bed sediment and tissue, and ecological studies (Gilliom et al., 1995). Sediment sampling is an integral part of both the water column and the bed sediment studies, and substrate conditions (i.e., stream bottom sediment) are an integral part of ecological habitat assessment. Suspended sediment is a targeted characteristic at all basic fixed sampling sites and intensive fixed sampling sites. Bed sediment is a targeted characteristic at all basic fixed sites, intensive fixed sites, and bed sediment sites. The sampling data collected on sediment are adequate to characterize suspended sediment in streams in each study unit. Bed sediment sampling is conducted primarily to measure trace elements and hydrophobic organic contaminants (Shelton and Capel, 1994). Site selection for bed sediment sampling considers factors such as depositional zones for fine-grained particles and wadability (Shelton and Capel, 1994). Such a sampling strategy is probably inadequate for measuring bed sediment loads.

The study units differed in their reporting of findings related to suspended sediment, even though all collected sediment data. Suspended sediment is not one of the seven water quality components being compared among study units (i.e., national synthesis topics), so whether a study unit reported sediment findings depended on whether this is a major local issue. In the first 36 summary reports released by the Cycle I study units, only 8 indicated that sediment was a major local issue (Central Columbia Plateau, Albemarle-Pamlico Drainages, Willamette Basin, Red River of the North Basin, Upper Snake River Basin, Lake Erie-Lake St. Clair Drainages, Upper Mississippi River Basin, and Upper Colorado River Basin). Some regions where agriculture is a major land use, such as the Eastern Iowa Basins and Lower Illinois River Basin, did not report any findings regarding sediment in streams.

Similarly, a national synthesis of sediment in surface waters is not planned for Cycle II of NAWQA. At the start of the program, one of the first planned national synthesis reports was to be on nutrients and sediments (Leahy and Wilber,

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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1991). However, the sediment component was subsequently dropped as part of that national synthesis topic. It seems that this decision was primarily a resource issue. It has been suggested that the USGS has had a diminished ability to conduct sediment transport research in recent decades and that it has only limited expertise in sediments (Robert Hirsch, USGS, personal communication, 1999). Rather than diverting resources to acquire this expertise, the decision was made to focus on those areas in which USGS expertise was strongest.

In Cycle II, sediment data will continue to be collected in water column and bed sediment sampling (Gilliom et al., 2000b). A planned study of the effects of changes in agricultural management practices on trends in streams will include suspended sediment. However, suspended sediment is not included in the study of the effects of urbanization on trends in streams. Sediment is, however, a significant issue in areas undergoing rapid development.

Assessment

The USGS is in a favorable position to provide leadership in sediment monitoring and interpretation. The subject of sediment is one that is critical to many USGS activities (Gray et al., 1997), and research on sediment-related topics is conducted by all four USGS divisions. Furthermore, the USGS is not the only agency conducting sediment research. The USBR undertakes technical studies to plan and design water resource facilities such as dams and reservoirs, to improve operation and maintenance of existing facilities, and to restore fish and wildlife health (Yang and Young, 1997). The Bureau of Land Management (BLM) is studying sediment as it relates to riparian health, abandoned mine land restoration, and salinity control (USGS-BLM, 1997). USDA’s Agricultural Research Service conducts research on soil erosion from agricultural lands and the movement of sediment to water resources. It also develops management practices and strategies for protecting water resources from agricultural pollutants such as sediment. However, these agencies lack the monitoring and scope necessary to describe status and trends of sediment in water resources of the United States.

Sedimentation has significant physical and budgetary effects on the ability of the USACE to accomplish its missions of keeping rivers and harbors navigable and maintaining its reservoirs (Garrett, 1997). The Waterways Experiment Station conducts research related to hydraulic and sedimentation engineering in rivers, streams, and reservoirs. Technical areas include alluvial channel and floodplain development, integrated river basin management for stabilization and restoration, and improved hydraulic design methods. The work is accomplished with the aid of numerical and physical models and field investigations. The USACE also develops equipment and procedures for collecting and analyzing sediment in conjunction with other agencies, including the USGS, as part of the Federal Interagency Sedimentation Project. The USGS participates in this project and helps

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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organize a periodic Federal Interagency Sedimentation Conference that has been held seven times since 1947.

Conclusion

The USGS can do more to expand the knowledge base of the impacts of sediment on water quality and on the relationships between land use, hydrology, and sediment loadings. Sediment is identified by states as the leading source of impairment in streams and rivers. NAWQA continues to collect data on suspended sediment in all of its Cycle I study units, but data are not being synthesized so that regional or national implications can be made. Programs for reducing soil erosion from agriculture and urban or suburban development could benefit by a better understanding of the linkages between land use and sedimentation and of where sedimentation is impairing aquatic health.

Monitoring for Particle-Associated Contaminants

During Cycle I, NAWQA sampled for particle-associated constituents (e.g., trace elements, organochlorine compounds, polycyclic aromatic hydrocarbons) in all study units by sampling streambed sediments, whole fish, and bivalve soft tissues (usually Corbicula). A synthesis of the pesticide and polychlorinated biphenyl (PCB) component of this research in the first 20 Cycle I study units has recently been completed (Wong et al., 2000). This study presents a valuable overview of the occurrence of these compounds and their relationship to patterns of land use in the watershed. This sampling strategy will not be continued during Cycle II because several deficiencies were determined that limited its use in detecting trends, such as high variability in concentrations in bed sediments at a given site; the fact that both sediments and fish move in a stream and hence their geographic history is unknown; and an absence of target fish or bivalve species at study sites. Instead, a paleolimnological approach will be used to better detect trends in particle-associated constituents during Cycle II (Gilliom et al., 2000b). One to three sediment cores will be taken from 66 lakes or reservoirs chosen as basin integrators or as indicators of urban, agricultural, or reference conditions. Concentrations at several depths in the dated core will be used to assess trends in particle-associated constituents. The committee feels that this is a wise approach for detecting trends in levels of contaminants in sediments and linking those trends with watershed conditions. However, it provides no information on trends in contamination of aquatic biota eaten by humans. Other programs with greater responsibility for human health will have to take responsibility for monitoring and analyzing such trends.

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

Recommendations

  • Develop a monitoring program in each Cycle II study unit to provide information on fluxes of sediment and sorbed pollutant discharges, identify trends in sediment and sorbed contaminant loads, and allow other more appropriate agencies to assess the hazards to humans and other biota of sediment and sorbed pollutants.

  • Synthesize existing habitat survey data to quantify the extent of habitat impairment resulting from excess sedimentation in Cycle II study units, and investigate the relationship between habitat impairment and land use.

  • Make sediment a national synthesis topic (i.e., summarize and synthesize findings on sediment and sediment-related pollutants) and provide insights for the nation that can be used by policy makers to maximize the benefits of state and federal conservation resources, while admitting to the shortcomings of current data collection.

  • Provide summaries of all study unit sediment data, as with other contaminants. This is of particular importance for watersheds that must develop a TMDL for sediment.

  • Expand USGS’s internal expertise in sediment monitoring and interpretation to provide a national leadership role for this important area of water quality research, and work with other local, state, and federal agencies to identify and conduct research on important sediment-related issues.

CONCLUSIONS AND RECOMMENDATIONS

In Cycle II, it has been proposed that NAWQA increase the focus on those waters that serve as sources of potable water. The committee concurs with this general strategy, as well as that of focusing on those sources most likely to be impacted by heavy urban and agricultural activities. The committee also finds that the proposal to establish a national drinking water team within NAWQA as it enters Cycle II is both logical and appropriate. However, the committee does not feel, given the limited resources for this program, that NAWQA should enter the area of human risk assessment, as currently proposed in Objective S4. NAWQA has extensive expertise in designing and conducting sampling programs, synthesizing data, and assessing relationships between land use and water quality. To extend its work into risk assessment, an often contentious and litigious topic for regulatory agencies such as EPA, would require the USGS to invest in new expertise. The committee feels strongly that it would be more prudent for NAWQA to maintain its focus on its established strengths and to collaborate as necessary and appropriate with other agencies that already have the requisite risk assessment expertise in-house.

The committee strongly supports the priority issues already selected for the national synthesis component of NAWQA, (i.e., pesticides, nutrients, volatile

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×

organic compounds, trace elements, ecological synthesis; see statement of task). Further conclusions and recommendations are summarized below related to additions of contaminants to these priorities and, in particular, the addition of sediment as a national synthesis priority.

Despite the possibility that resources are going to be limiting for the NAWQA Cycle II program, the committee is pleased that the NAWQA team proposes to add some new contaminants to its list of constituents to be monitored in Cycle II. In this regard, the committee agrees that all three groups of pesticides proposed for monitoring in Cycle II are appropriate and warranted and should be added to this priority area. However, the committee feels strongly that there is a need to develop a mechanism for prioritizing all contaminants under consideration relative to one another so that optimum use can be made of the available resources. Furthermore, NAWQA should focus on monitoring sites at which similar or equivalent data are not already being collected by other agencies and for those contaminants for which there are known adverse impacts on human health and/or the environment. Other specific recommendations related to status assessments of water quality in Cycle II include the following:

  • Given the reduction in resources that necessitated a smaller suite of Cycle II study units, more emphasis on sampling in lakes, reservoirs, and coastal waters such as estuaries than already planned for Cycle II is not feasible. Hence, additional opportunities for partnering with other agencies should be sought. For example, NAWQA study units should focus on collaborating with and using data collected by other organizations, such as state agencies, EPA, USBR, USACE, and NOAA, in assessing the importance of pollutant loadings and surface water-groundwater interactions to water quality in lakes, reservoirs, and estuaries. In this manner, some degree of understanding of the relevant processes may be obtained with a minimum of NAWQA expenditures.

  • Current sampling in lakes and reservoirs that are important public supply sources should be maintained, and other important lake-reservoir public supply sources should be included if resources become available (this might involve a reassessment of which lakes or reservoirs to sample). As noted in Chapter 2, the LPA-SQA methodology could be used to help determine which lakes and reservoirs to study.

  • From measurements of inflow and outflow, NAWQA should compile information on the retention of sediments and other contaminants by lakes and reservoirs.

  • NAWQA should consider significantly revising the language (and intent) of Objective S4 to fit its strengths, for example: “Describe the occurrence and co-occurrence of contaminants (contaminant mixtures) in the environment that should be considered by other agencies for toxicological research and risk assessments.” (Various iterations of the current objective imply the NAWQA would enter into the field of risk assessment.)

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×
  • NAWQA should focus on filling gaps in knowledge (e.g., by providing information in previously unstudied areas or by providing information on the temporal and spatial variability of a contaminant’s occurrence and concentrations), rather than on new contaminants for which methods have not been developed.

  • The decision about which additional contaminants to study in Cycle II should be made with direct input from EPA and other agencies so that the most important contaminants from a policy-making standpoint can be monitored.

  • The NAWQA team should develop a procedure either jointly or with the direct input of EPA or other agencies whereby all contaminants can be evaluated and/or ranked according to a variety of criteria, including known or suspected health or ecological effects, mass of the contaminant released to the environment, availability of analytical methods, and other factors, as part of the decision process for inclusion of new contaminants for monitoring.

  • NAWQA should not add pharmaceuticals or additional HPV industrial chemicals to the list of contaminants to be monitored until reliable sampling protocols and analytical methods can be validated.

  • In the selection and monitoring of MeHg sites already planned for Cycle II, consideration should be given to atmospheric inputs of mercury. NAWQA should also consider sampling MeHg concentration in the water, since this appears to be a good predictor of bioaccumulation of mercury in fish.

  • The committee strongly supports the addition of waterborne pathogens and indicator microorganisms to the list of contaminants that will be monitored in Cycle II. However, NAWQA should reconsider its previously proposed microbiological sampling program (described in Francy et al., 2000a) that includes more detailed sampling, because waterborne pathogens are of such known import to human health.

  • Groundwater sites that have microbiological indicator-positive samples should be tested for the presence of specific waterborne pathogens. A subset of sites that are indicator-negative should also be tested for pathogens in a manner that will allow multivariate statistical analysis of the data, as performed in the pilot study by Francy et al. (2000b).

  • NAWQA should include a monitoring program in each Cycle II study unit to provide information on fluxes of sediment and sorbed pollutant discharges, identify trends in sediment and sorbed contaminant loads, and allow other more appropriate agencies to assess the hazards to humans and other biota of sediment and sorbed pollutants. (This is of particular importance for watersheds that will require a TMDL for sediment.)

  • Existing habitat survey data should be synthesized to quantify the extent of habitat impairment resulting from excess sedimentation in Cycle II study units and to investigate the relationship between habitat impairment and land use (and if possible, from Cycle I data as well).

Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
×
  • NAWQA should make sediment a national synthesis topic (i.e., summarize and synthesize findings on sediment and sediment-related pollutants) and provide implications for the nation that can be used by policy makers to maximize the benefits of state and federal conservation resources.

  • The USGS should expand its internal expertise on sediment monitoring and interpretation to provide a national leadership role for this important area of water quality research and work with other local, state, and federal agencies to identify and conduct research on important sediment-related issues.

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Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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Suggested Citation:"3 NAWQA Cycle II Goals - Status." National Research Council. 2002. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, DC: The National Academies Press. doi: 10.17226/10267.
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The U.S. Geological Survey (USGS) established the National Water Quality Assesment (NAWQA) program in 1985 to assess water quality conditions and trends in representative river basins and aquifers across the United States. With this report, the NRC's Water Science and Technology Board has provided advice to USGS regarding NAWQA five separate times as the program evolved from an unfunded concept to a mature and nationally--recognized program in 2002. This report assesses the program's development and representative accomplishments to date and makes recommendations on opportunities to improve NAWQA as it begins its second decade of nationwide monitoring.

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